I have a 2010 Jetta wagon, 2.0 TDI, 6sp manual. It's been having completely random fluctuations in fuel economy. I'm at a loss and hoping for some ideas. Here's the story:
- I got it (salvage) in October 2016. First trip was in November with a 12 hr drive one way and I averaged 45 mpg without trying. I was happy
- December I took a few short trips and found I was only getting 38 mpg. I wasn't so happy But I live in Michigan and figured it must just be the winterized diesel or the sub-zero temps.
- First of January I drove to Texas and back, tried Lucas injector cleaner, got diesel down south, enjoyed 70+ temps, was careful to avoid lead-foot - made no difference. Averaged 37 mpg.
- Couple weeks later I took a two hour trip in northern Michigan, snow and ice, cold temps, got 42 mpg.
- A week later I took a similar trip and got 38 mpg.
- A week later I drove to Florida. Got 42 on the way down, 36 ish on the way back. Absolutely no difference between these except I was going south one way and north the other.
- I was out of town for a few months and got back to driving it mid-2017. Getting about 38 mpg, and also noticed front and rear control arms were bad. I decided to go all-out and threw about $1k in suspension at it - struts/shocks, mounts, springs, bushings, arms, etc. etc. New tires. Absolutely no difference in mpg. One day it gets 38, the next 45.
- October I drove it 5 hrs and got 46 mpg. Sat over the weekend and then drove it 16 hrs and got 38 mpg. Again, no difference at all between the trips except the day of the week!
- December I drove to Phoenix, AZ (from Michigan). On the way out the clutch started slipping and the DMF started rattling. Figured I didn't want to be stranded on the way back so I had the clutch/flywheel replaced in Phoenix. I wondered if possibly the slipping clutch or DMF had anything to do with the MPG. Nope. Got the same coming as going - fluctuating day-to-day by as much as 6 mpg.
- Lately it's been short (1-2 hr) trips. One day I might get 36-38, the next day, on the same tank of fuel, same road, I'll get 42-44.
I've pretty well ruled out breaks and suspension, so now I'm wondering if it's something engine related.
Are these fluctuations in MPG normal? I haven't come across anyone else saying anything about this. My mom has a 06 1.9 TDI 5sp and she gets very consistent mpg, no matter the load, season, or driving conditions.
Obviously I'd like to get rid of the fluctuation, but I'd also like to get back to the original 45 mpg goodness!
Sorry for rattling on. Hope someone has some ideas. Thanks!
- I got it (salvage) in October 2016. First trip was in November with a 12 hr drive one way and I averaged 45 mpg without trying. I was happy
- December I took a few short trips and found I was only getting 38 mpg. I wasn't so happy But I live in Michigan and figured it must just be the winterized diesel or the sub-zero temps.
- First of January I drove to Texas and back, tried Lucas injector cleaner, got diesel down south, enjoyed 70+ temps, was careful to avoid lead-foot - made no difference. Averaged 37 mpg.
- Couple weeks later I took a two hour trip in northern Michigan, snow and ice, cold temps, got 42 mpg.
- A week later I took a similar trip and got 38 mpg.
- A week later I drove to Florida. Got 42 on the way down, 36 ish on the way back. Absolutely no difference between these except I was going south one way and north the other.
- I was out of town for a few months and got back to driving it mid-2017. Getting about 38 mpg, and also noticed front and rear control arms were bad. I decided to go all-out and threw about $1k in suspension at it - struts/shocks, mounts, springs, bushings, arms, etc. etc. New tires. Absolutely no difference in mpg. One day it gets 38, the next 45.
- October I drove it 5 hrs and got 46 mpg. Sat over the weekend and then drove it 16 hrs and got 38 mpg. Again, no difference at all between the trips except the day of the week!
- December I drove to Phoenix, AZ (from Michigan). On the way out the clutch started slipping and the DMF started rattling. Figured I didn't want to be stranded on the way back so I had the clutch/flywheel replaced in Phoenix. I wondered if possibly the slipping clutch or DMF had anything to do with the MPG. Nope. Got the same coming as going - fluctuating day-to-day by as much as 6 mpg.
- Lately it's been short (1-2 hr) trips. One day I might get 36-38, the next day, on the same tank of fuel, same road, I'll get 42-44.
I've pretty well ruled out breaks and suspension, so now I'm wondering if it's something engine related.
Are these fluctuations in MPG normal? I haven't come across anyone else saying anything about this. My mom has a 06 1.9 TDI 5sp and she gets very consistent mpg, no matter the load, season, or driving conditions.
Obviously I'd like to get rid of the fluctuation, but I'd also like to get back to the original 45 mpg goodness!
Sorry for rattling on. Hope someone has some ideas. Thanks!